Selamectin is a semi-synthetic macrocyclic lactone that is widely used to prevent heartworm infection. Selamectin activates glutamate-gated chloride channels in neurons and pharyngeal muscles to prevent heartworm, Lymphatic filariae, and nematode infection. Selamectin is also a potent P-glycoprotein substrate and a P-glycoprotein inhibitor with an IC50 of 120 nM.

[1] Patsharaporn T Sarasombath, et al. First study of topical selamectin efficacy for treating cats naturally infected with Brugia malayi and Brugia pahangi under field conditions. Parasitol Res. 2019 Apr;118(4):1289-1297.

[2] J Griffin, et al. Selamectin is a potent substrate and inhibitor of human and canine P-glycoprotein. J Vet Pharmacol Ther. 2005 Jun;28(3):257-65.